The mutagenicity of 1,2,7,8-diepoxyoctane (DEO) was investigated using Chinese hamster lung cells. 6-thioguanine resistance and chromosome aberration were induced. DEO was found to readily form adducts with radiolabeled nucleotides, as demonstrated through thin-layer chromatography in DEO/nucleotides mixtures. The mutagenic specificity of DEO is apparently related to the compound's ability to bind DNA.